IEC 61400-24:2010

Wind turbines - Part 24: Lightning protection

IEC 61400-24:2010(E) applies to lightning protection of wind turbine generators and wind power systems. Defines the lightning environment for wind turbines and application of the environment for risk assessment for the wind turbine. Defines requirements for protection of blades, other structural components and electrical and control systems against both direct and indirect effects of lightning. Recommends test methods to validate compliance. Provides guidance on the use of applicable lightning protection, industrial electrical and EMC standards including earthing. Provides guidance regarding personal safety. Makes normative references to generic standards for lightning protection, low-voltage systems and high-voltage systems for machinery and installations and EMC.
This publication is of high relevance for Smart Grid.

General Information

• Status: Published
• Publication Date: 15-Jun-2010
• ICS: 27.180 - Wind turbine energy systems
• Technical Committee: TC 88 - Wind energy generation systems
• Current Stage: DELPUB - Deleted Publication
• Completion Date: 03-Jul-2019

Relations

• Revised: IEC 61400-24:2019 - Wind energy generation systems - Part 24: Lightning protection
• Effective Date: 05-Sep-2023

Standards Content (Sample)

IEC 61400-24


®

Edition 1.0 2010-06



INTERNATIONAL



STANDARD





Wind turbines –
Part 24: Lightning protection




IEC 61400-24:2010(E)

---------------------- Page: 1 ----------------------
THIS PUBLICATION IS COPYRIGHT PROTECTED

Copyright © 2010 IEC, Geneva, Switzerland



All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form

or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from
either IEC or IEC's member National Committee in the country of the requester.
If you have any questions about IEC copyright or have an enquiry about obtaining additional rights to this publication,

please contact the address below or your local IEC member National Committee for further information.



IEC Central Office
3, rue de Varembé

CH-1211 Geneva 20

Switzerland
Email: [e-mail]
Web: www.iec.ch

About the IEC
The International Electrotechnical Commission (IEC) is the leading global organization that prepares and publishes
International Standards for all electrical, electronic and related technologies.

About IEC publications
The technical content of IEC publications is kept under constant review by the IEC. Please make sure that you have the
latest edition, a corrigenda or an amendment might have been published.
ƒ Catalogue of IEC publications: www.iec.ch/searchpub
The IEC on-line Catalogue enables you to search by a variety of criteria (reference number, text, technical committee,…).
It also gives information on projects, withdrawn and replaced publications.
ƒ IEC Just Published: www.iec.ch/online_news/justpub
Stay up to date on all new IEC publications. Just Published details twice a month all new publications released. Available
on-line and also by email.
ƒ Electropedia: www.electropedia.org
The world's leading online dictionary of electronic and electrical terms containing more than 20 000 terms and definitions
in English and French, with equivalent terms in additional languages. Also known as the International Electrotechnical
Vocabulary online.
ƒ Customer Service Centre: www.iec.ch/webstore/custserv
If you wish to give us your feedback on this publication or need further assistance, please visit the Customer Service
Centre FAQ or contact us:
Email: [e-mail]
Tel.: [phone]
Fax: [phone]

---------------------- Page: 2 ----------------------
IEC 61400-24


®

Edition 1.0 2010-06



INTERNATIONAL



STANDARD





Wind turbines –
Part 24: Lightning protection



INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
XG
ICS 27.180 ISBN 978-2-88910-969-2
® Registered trademark of the International Electrotechnical Commission

---------------------- Page: 3 ----------------------
– 2 – 61400-24 © IEC:2010(E)



CONTENTS

FOREWORD.8


1 Scope.10

2 Normative references .10

3 Terms and definitions .12


4 Symbols and units .18

5 Abbreviations .20

6 Lightning environment for wind turbine .20

6.1 General .20
6.2 Lightning current parameters and lightning protection levels (LPL) .20
7 Lightning exposure assessment.22
7.1 General .22
7.2 Assessing the frequency of lightning affecting a wind turbine .23
7.3 Assessing the risk of damage.26
7.3.1 Basic equation.26
7.3.2 Assessment of risk components due to flashes to the wind turbine
(S1) .27
7.3.3 Assessment of the risk component due to flashes near the wind
turbine (S2) .27
7.3.4 Assessment of risk components due to flashes to a service line
connected to the wind turbine (S3) .27
7.3.5 Assessment of risk component due to flashes near a service line
connected to the wind turbine (S4) .28
8 Lightning protection of subcomponents.29
8.1 General .29
8.2 Blades.29
8.2.1 General .29
8.2.2 Requirements .29
8.2.3 Verification .29
8.2.4 Protection design considerations .30
8.2.5 Test methods.32
8.3 Nacelle and other structural components.32
8.3.1 General .32
8.3.2 Hub .33

8.3.3 Spinner.33
8.3.4 Nacelle .33
8.3.5 Tower .34
8.3.6 Testing methods .34
8.4 Mechanical drive train and yaw system.34
8.4.1 General .34
8.4.2 Bearings.35
8.4.3 Hydraulic systems .35
8.4.4 Spark gaps and sliding contacts .35
8.4.5 Testing .35
8.5 Electrical low-voltage systems and electronic systems and installations .36
8.5.1 General .36
8.5.2 LEMP protection measures (LPMS) .36
8.5.3 Lightning protection zones (LPZ) .37

---------------------- Page: 4 ----------------------
61400-24 © IEC:2010(E) – 3 –


8.5.4 Equipotential bonding within the wind turbine .37

8.5.5 Shielding and line routing .37

8.5.6 Coordinated SPD protection .38

8.5.7 Testing methods for system immunity tests.41

8.6 Electrical high-voltage (HV) power systems.41

9 Earthing of wind turbines and wind farms .43

9.1 General .43

9.1.1 Basic requirements.43

9.1.2 Earth electrode arrangements.43

9.1.3 Earthing system impedance.44
9.2 Equipotential bonding.44
9.2.1 General .44
9.2.2 Lightning equipotential bonding for metal installations .44
9.2.3 Electrically insulated LPS .45
9.3 Structural components.45
9.3.1 General .45
9.3.2 Metal tubular type tower .45
9.3.3 Metal reinforced concrete towers .45
9.3.4 Lattice tower.46
9.3.5 Systems inside the tower.46
9.3.6 Concrete foundation .46
9.3.7 Rocky area foundation.47
9.3.8 Metal mono-pile foundation.47
9.3.9 Offshore foundation .47
9.4 Electrode shape dimensions.47
9.5 Wind farms.48
9.6 Execution and maintenance of the earthing system .48
10 Personal safety .49
11 Documentation of lightning protection system.50
11.1 General .50
11.2 Documentation necessary during assessment for design evaluation .50
11.2.1 General documentation.50
11.2.2 Documentation for rotor blades.51
11.2.3 Documentation of mechanical systems .51
11.2.4 Documentation of electrical and electronic systems .51

11.2.5 Documentation of earthing and bonding systems .51
11.2.6 Documentation of nacelle cover, hub and tower lightning protection
systems.51
11.3 Site specific information .52
11.4 Documentation to be provided for LPS inspections .52
11.4.1 Visual LPS inspection report.52
11.4.2 Complete LPS inspection report .52
11.5 Manuals .52
12 Inspection of lightning protection system .52
12.1 Scope of inspection .52
12.2 Order of inspections .53
12.2.1 General .53
12.2.2 Inspection during production of the wind turbine .53
12.2.3 Inspection during installation of the wind turbine.53

---------------------- Page: 5 ----------------------
– 4 – 61400-24 © IEC:2010(E)


12.2.4 Inspection during commissioning of the wind turbine and periodic

inspection.53

12.2.5 Inspection after dismantling or repair of main parts.54

12.3 Maintenance.54

Annex A (informative) The lightning phenomenon in relation to wind turbines .55

Annex B (informative) Lightning exposure assessment .66

Annex C (informative) Protection methods for blades.84

Annex D (informative) Test specifications .96


Annex E (informative) Application of lightning protection zones (LPZ) concept at a

wind turbine .119
Annex F (informative) Selection and installation of a coordinated SPD protection in
wind turbines .124
Annex G (informative) Additional information on bonding and shielding and installation
technique.128
Annex H (informative) Testing methods for system level immunity tests. 133
Annex I (informative) Earth termination system . 135
Annex J (informative) Example of defined measuring points. 143
Annex K (informative) Typical lightning damage questionnaire. 145
Annex L (informative) Monitoring systems.148
Annex M (informative) Guidelines for small wind turbines – Microgeneration. 149
Bibliography.150

Figure 1 – Collection area of the wind turbine .24
Figure 2 – Effective height, H, of wind turbine exposed on a hill.24
Figure 3 – Collection area of wind turbine of height H and another structure of height
a
H connected by underground cable of length L .26
b c
Figure 4a – Squirel cage induction generator (SCIG) .42
Figure 4b – Wound rotor induction generator (WRIG).42
Figure 4 – Examples of placement of HV arresters in two typical main electrical circuits
of wind turbines .42
Figure A.1 – Processes involved in the formation of a cloud-to-ground flash .57
Figure A.2 – Typical profile of a negative cloud-to-ground flash (not to scale).58
Figure A.3 – Definitions of short stroke parameters (typically T < 2 ms).58
2

Figure A.4 – Definitions of long stroke parameters (typically 2 ms < T < 1 s)
long
(Figure A.2 in IEC 62305-1) .59
Figure A.5 – Possible components of downward flashes (typical in flat territory and to
lower structures) (Figure A.3 in IEC 62305-1) .60
Figure A.6 – Typical profile of a positive cloud-to-ground flash .60
Figure A.7 – Typical profile of a negative upward initiated flash .61
Figure A.8 – Possible components of upward flashes (typical to exposed and/or higher
structures) (Figure A.4 in IEC 62305-1).63
Figure C.1 – Types of wind turbine blades .85
Figure C.2 – Lightning protection concepts for large modern wind turbine blades .87
Figure C.3 – Lightning induced voltages between lightning conductor or structure and
sensor wiring .90
Figure D.1 – Initial leader attachment test setup A (specimen should be tested in
several positions representing different directions of the approaching leader).99

---------------------- Page: 6 ----------------------
61400-24 © IEC:2010(E) – 5 –


Figure D.2 – Possible orientations for the initial leader attachment test setup A.100

Figure D.3 – Leader connection point must be away from test specimen. 101


Figure D.4 – Initial leader attachment test setup B. 102

Figure D.5 – Arrangement for local protection device (e.g. diverter) – Evaluations test

setup C.103

Figure D.6 – Typical switching impulse voltage rise to flashover (100 μs per division) . 104


Figure D.7 – Swept channel test arrangement.108

Figure D.8 – Lightning impulse voltage waveform (Figure 6 in IEC 60060-1) . 108

Figure D.9 – Lightning impulse voltage waveform showing flashover on the wave front

(Figure 7 in IEC 60060-1) .109
Figure D.10 – Typical jet diverting test electrodes.112
Figure D.11 – High-current test arrangement for non-conductive surfaces . 114
Figure D.12 – Example of an arrangement for conducted current tests . 117
Figure E.1 – Rolling sphere model .120
Figure E.2 – Mesh with large mesh dimension for nacelle with GFRP cover. 121
Figure E.3 – Mesh with small mesh dimension for nacelle with GFRP cover. 121
Figure E.4 – Two cabinets both defined as LPZ 2 connected via the shield of a
shielded cable.122
Figure E.5 – Example: Division of wind turbine into different lightning protection zones .123
Figure E.6 – Example of how to document LPMS division of electrical system into
protection zones with indication of where circuits cross LPZ boundaries and showing
the long cables running between tower base and nacelle.123
Figure F.1 – Point-to-point installation scheme (Figure 53E in IEC 60364-5-53). 125
Figure F.2 – Earthing connection installation scheme (Figure A.1 in IEC 60364-5-53).125
Figure G.1 – Two control cabinets located on different metallic planes inside a nacelle .128
Figure G.2 – Magnetic coupling mechanism.129
Figure G.3 – Measuring of transfer impedance. 131
Figure H.1 – Example circuit of a SPD discharge current test under service conditions. 134
Figure H.2 – Example circuit of an induction test due to lightning currents . 134
Figure I.1 – Minimum length (l ) of each earth electrode according to the class of LPS
1
(Figure 2 in IEC 62305-3) .138
Figure I.2 – Frequency dependence on the impedance to earth (adapted from Cigré
139
WG C.4.4.02 July 2005 [49]) .

Figure J.1 – Example of measuring points.143
Figure K.1 – Blade outlines for marking locations of damage . 147

Table 1 – Maximum values of lightning parameters according to LPL (Table 5 in
IEC 62305-1) .21
Table 2 – Minimum values of lightning parameters and related rolling sphere radius
corresponding to LPL (Table 6 in IEC 62305-1).22
Table 3 – Collection areas A and A of service line depending on whether aerial or
I i
buried (corresponds to Table A.3 in IEC 62305-2).26
Table 4 – Parameters relevant to the assessment of risk components for wind turbine
(corresponds to Table 8 in IEC 62305-2).28

---------------------- Page: 7 ----------------------
– 6 – 61400-24 © IEC:2010(E)


Table 5 – Minimum dimensions of conductors connecting different bonding bars/points

or connecting bonding bars/points to the earth termination system (Table 8 in

IEC 62305-3) .45

Table 6 – Minimum dimensions of conductors connecting internal metal installations to

the bonding bar/point (Table 9 in IEC 62305-3).45

Table 7 – LPS General inspection intervals.54


Table A.1 – Cloud-to-ground lightning current parameters (adapted from Table A.1 in

IEC 62305-1) .59

Table A.2 – Upward initiated lightning current parameters .62

Table A.3 – Summary of the lightning threat parameters to be considered in the

calculation of the test values for the different LPS components and for the different
LPL (Table D.1 in IEC 62305-1) .64
Table B.1 – Sources of damage, types of damage and types of loss according to point
of strike (corresponds to Table 1 in IEC 62305-2) .67
Table B.2 – Risk in a wind turbine for each type of damage and of loss  (corresponds
to Table 2 in IEC 62305-2).68
Table B.3 – Values of probability, P , that a lightning flash to a wind turbine will cause
A
shock to living beings due to dangerous touch and step voltages (corresponds to
Table B.1 in IEC 62305-2).71
Table B.4 – Values of probability, P , depending on the protection measures to reduce
B
physical damage (corresponds to Table B.2 in IEC 62305-2) .71
Table B.5 – Values of probability P as a function of the LPL for which the SPDs
SPD
are designed (Table B.3 in IEC 62305-2) .72
Table B.6 – Values of probability, P , depending on the resistance, R , of the cable
LD S
screen and the impulse withstand voltage, U , of the equipment (Table B.6 in
W
IEC 62305-2) .73
Table B.7 – Values of probability, P , depending on the resistance, R , of the cable
LI S
screen and the impulse withstand voltage, U , of the equipment (Table B.7 in
W
IEC 62305-2) .74
Table B.8 – Values of reduction factors r and r as a function of the type of surface of
a u
soil or floor (corresponds to Table C.2 in IEC 62305-2).76
Table B.9 – Values of reduction factor r as a function of provisions taken to reduce
p
the consequences of fire (Table C.3 in IEC 62305-2) .76
Table B.10 – Values of reduction factor r as a function of risk of fire of the wind
f
turbine (corresponds to Table C.4 in IEC 62305-2) .76
Table B.11 – Values of factor h increasing the relative amount of loss in presence of
Z
a special hazard (corresponds to Table C.5 in IEC 62305-2).77

Table B.12 – Typical mean values of L , L and L (corresponds to Table C.7 in
t f o
IEC 62305-2) .77
Table B.13 – Values of factor K as a function of the characteristics of the shielded
d
service line (corresponds to Table D.1 in IEC 62305-2).79
Table B.14 – Values of factor K as a function of the protection measures (Table D.2
p
in IEC 62305-2) .79
Table B.15 – Impulse withstand voltage U as a function of the type of cable (Table
W
D.3 in IEC 62305-2) .79
Table B.16 – Impulse withstand voltage U as a function of the type of apparatus
W
(Table D.4 in IEC 62305-2) .79
Table B.17 – Values of probability P’ , P’ , P’ and P’ as function of the failure
B C V W
current I (Table D.5 in IEC 62305-2) .80
a
Table C.1 – Material, configuration and minimum nominal cross-sectional area of air-
termination conductors, air-termination rods and down conductors (corresponds to
)
Table 6 in IEC 62305-3, future edition 2 ).92

---------------------- Page: 8 ----------------------
61400-24 © IEC:2010(E) – 7 –


Table C.2 – Physical characteristics of typical materials used in lightning protection

systems (Table D.2 in IEC 62350-1) .93

Table C.3 – Temperature rise [K] for different conductors as a function of W/R (Table

D.3 in IEC 62305-1) .94


Table E.1 – Definition of lightning protection zones according to IEC 62305-1 . 119

Table F.1 – Discharge and impulse current levels for TN systems given in IEC 60364-

5-53.
...